Two-level



3 Sheets-Sheet l lr 50.5 KJ. v...,.\ Y .5470 7 9 5 wiwi /4 5 y /4\ l .1, l HAMM June 19. 1928.v

Filed April 50. 1920 June 19, 1928. 1,674,062

' c. L. RAYFIELD TWO -LEIVEL- MULTI JET CARBURETO R Filed April 5.o. 1920 :s sheets-sheet -2 `lune 19, 1928.V

C. L. RAYFIELD` TWO-LEVEL MULTIJET CARBURETOR 5 .Sheets-Shea?l 5 Filed April 30. 1920 l di 5 v 70 ,7

E @ww Patented June 19, 1928.

UNITE* star errA erica,

ACHAR-LES L. RAYFIELD, OF CHICAGO, ILLINOIS, ASSIGNOR, BY MESNE ASSIGNMENTS, TO GENESEE CARBUREIER COMPANY, 0F FLINT, MICHIGAN, A CORPORATION OF INDIANA.

i TWO-LEVELIMULTIJET CARBURETOR.

Application filed April 30, 1920. Serial No. 377,922.

This invention relates to that type of retor embodying the principles of my invencarburetor wherein a supply of fuel is maintained at two' diiferent levels in chambers communicating with one another, onel cha-mber overflowing through a standpipe into the other and withthe inlet of fuel to the carburetor controlled by a float mechanism within one of the chambers. Furthermore, this carburetor involves the use of a compound nozzle having a plurality of fuel jets, different parts of which are in communication with different fuel supply chambers and yet with the outlets for the respective jetsdisposed substantially at the same point in a Venturi tube of the carbureting chamber leading to the manifold of an engine to best utilize the aspiration effect of flow through the carburetor.

The carburetor also comprehends a novel arrangement of passages from one of the chambers for. supplying fuel beyond the throttle valve .for priming the engine during y starting as well as an ingenious arrangement and design of parts contributing toward theproper functioning of the device as an eiiicient and complete mechanism for supplying-an explosive mixture of the proper proportions to an internal combustion engine for the various conditions of operation thereof. f

lt is an object therefore of this invention to provide a carburetor having a plurality of fuel supply chambers for supplying fuel to avnumber of fuel jets in a compound nozzle whereby the assembly of fuel jets affords a compensating supply means for the fuel toV properly proportion thepquantity of fuel admitted to the carburetor for various operating conditions ofthe engine. y

it is a furthery object of this invention to provide a carburetorr free from complicated moving parts and operating automatically to properly carburet the airentering the carburetor for admission to the engine.

Other and further important objects of this invent-ion will be apparent from the disclosures in the drawings and specification.

My invention (in azpreferred form) is illustrated in the drawings and hereinafter more fully described.

Dra/wings.

Figure l is a side elevation of a earbution.

Figure 2 is an enlarged central lvertical section taken through the carburetor with parts omitted and parts shown in elevaf tion.

Figure Sis a central vertical section with parts omitted and parts shown in elevation taken on the line 3 3 of Fig. 2.

Figure ll is a sectional detail on line 4 4: of Figure 2 with parts omitted and parts shown in elevation.

Figure 5 is a fragmentary detail section talien on line 5 5 of Figure 4.

Figure G is an enlarged fragmentary detail section on line 6 6 of Figure 4; with parts in elevation.

Figure 7 is an enlarged detail section taken through the fuel nozzle of the carburetor.

Description.

The carburetor consists of a main casing 1 cast as an integral piece of metal having therein a chamber 2 with an outlet 3 in which is disposed a Venturi tube 4 secured by set screw 5 and lock nut 6. Also disposed in said outlet is a throttle valve T on an op erating shaft 8 having a lever 9, and beyond said throttle valve the end of the casing is flanged as denoted by reference numeral 10 for attachement of the carburetor to the engine manifold.

Also formed within the casing 1 is an air inlet passage 11 provided with a butterfly valve 12 which is operated as a choker, and is'mounted on a shaft 13 having an operating handle 14; exterior of the casing. Formed at one side of the chamber 2 is an .overfiow or standpipe chamber l5 vented at l5*1 and having a drain aperture closed by a plug 1G in the lower end thereof, and at its upper end formed with an inlet passage 1T communicating into a fitting 18 in which is a screen 19, mounted on the end of a litting plug 20.

Attached to the casing 1 on the under side thereof is a float chamber casing 21 having an extension 22 which is extended to one side and beneath the overflow chamber 15 and said float chamber casing 2l is provided with a drain outlet normally closed by a closure plug 23.` Threaded into the floor 24 of the overflow casing as shown in detail in Figure 6 is an upright tube or standpipe 25, and slidable therethrough is a triangular stem 26 of a needle valve closure 27 which at its upper end registers with an inlet passage ofV a plug member 28 threaded into the top wall of the overflow casing and communicating with the inlet passage 17. Mounted on the upper end of the stem 26 below the needle valve closure 27 is a hood or cap 29 having apertures 30 therethrough, said hood fitting over, though spaced above and away Ytrom the upper end ot' the standpipe tube 25. The lower end of the stem 26 of said needle valve rests upon a pivoted bar 3l attached'upen a pivot tension 82 beneath the floor 24 within the side compartment 22 of the float chamber, and the end of said pivoted bar 81 is of yoke shape, and rests upon the upper surface oi a tloat "9 slidably OL) mounted within the 'lloat chamber to assume different levels therein according to the level of the fuel in said `tloat chamber.

As shown in Figures 2 and 7 the lloor of the chamber 2 formed to afford substantially a hub and threaded into the end thereof a tube provided with a sealing gasket 36. Threaded into the lower end ol said hub 34 is a plug 37 with -tling gasket 38 and engaged into said plug 37 is a downwardly entenda,ol tube 89, which projects through an apert Le in the floor or' the lleat chamber 2 and has threaded thereon in sealing relation, a nut 40. The float 38 of the lloat chamber slidably mounted upon said tube or stein Said tube 89 is provided with a port 41 near its upper end and another port 42 near its lower lend both within the float chamber 21, but with the lower port 42 normally submerged in the fuel within the float chamber and the upper ort 41 normally in the air space above thi,` llavel of the fuel.

Threaded into the upper end of the uprighttube of the main fuel nozzle is an inner tube 43, having apertures 43a 48 and said tube 43 is spaced from the outer tube to alord an annular chamber and extends downwardly to the same point as the tube member 35, and the outer tube 35 is provided with slits or outlet passages 44 at its upper end. lVithin the inner tube 48 is another tube 45 spaced therefrom to afford another annular chamber and said tube 45 at its lower end is threaded into the aperture of the member 87 and at .its upper end is provided with apertures 46. Inserted within the tube 45 and spaced inwardly therefrom. is the centra-l tube of the fuel nozzle which is denoted bythe reference numeral 47. The lower end of said central tube is secured into the lower end ot' the tube 39A and has a. plug closure 48 therein.

Said tube 47 near its lower end is provided with apertures 49 and at its upper end,

at the tip of the nozzle, has a spacing washer or collar 50 therearound which engages ywith the upper end of the tube 45 to hold the tubes spaced fromk one another and thusv afford an annular chamber therebetween.

It will be seen that the manner of assembly of the various tubes described, in the hub member 34, provides an annular chamber 51 Within said hub member coinmunicating with both of the annular chambers between the tubes 43 and 45, and the tubes 43 and 35.

As shown in detail in Figure 5 a passage 52 is formed in the casing 1 -inclining slightly downwardly to the chamber 51 and the passage 52 communicates with a vertical vent passage 53fformed in the wallV of the overflow chamber 15 and as shown, is closed by a "alibratcd plug 54. Threaded into the floor of the overflow chamber 15 shown in Figure 5 and communicating with the passage 52 is an apertured plug 55 form.- ing a seat `tor a needle valve closure 56, the stem 57 of which extends upwardly and is threaded into a plug 58 threaded through an ap wrt-ure in the top wall of the chamber 15. A detachable cap 59 is providedr over the upper apertured end of the plug 58 which by removal, gives access to the stem 57 for adjustment of the needlevalve. A cylindrical screen 6() is engaged in position concentrically about the needle valve 57, as its upper endenga ed around the lower end of the plug 58 an its lower end around the upper end of plug 55. Y

As shown yiin Figure 8 a passage 61 is boredfin the side ot the lloat chamber 21 which registers with a passage 62 in thecasing 1 and said passage 62 communicates into a lateral passage 68 which communicates through the inner wall of the casing 1 said passage 63 registering with a peripheral groove 64 on the .venturi 4. An air inlet port 65 is provided through the casing' 1 opposite to said passage 63 and also registering with said peripheral groove 64. T he communication between the passage 63 and the peripheral groove or passage is controlled by a manually adjustable needle valve 66 having a knurled headr67 and a spring impelled detent 68 to retain the same in adjusted position. Formed in the easing 1 at the side of the outlet extension 3 and communicating with passage 68, is a passage 69 which at its upper end is closed by a. plug 70, but which passage 69 communicates into a laterally directed passage 71 leading into the outlet end of' the carburetor beyond the throttle valve. Ther shaft 8,'is providedV with a passage 72 therethrough which registers with the passage 69 when the throttle valveJ 7 is closed, tus permitting a flow through the passage 6,9 to the passage 71.

As shown clearly in Figures 2 and 4 an air vent 73 for the float chamber 21 is pro- Utl 'vided in the floor of the chamber 2, and in the lower end of the float chamber 21 surrounding the tube 39 above the aperture 42 is a conical screen 74.-

Operation?.

The fuel is admitted into the carburetor by a pipe connection (not shown) through the fitting 20 flowing through the screen 19 and passage 17 past the open needle valve 27 and spilling over the hood 29 into the overflow chamber 15. `rIhe level of the fuel continues to rise in the overflow chamber 15 finally reaching a height such that it flows over and into the upper end of the standpipe 25 and downwardly therethrough into the float chamber 21, and as the floatchamberfills the float 33 is elevated until a predetermined level is reached such that said float operates the lever 31 to elevate the stem 26 of the needle valve 27, closing off the inlet of fuel to the overflow chamber. The apertures BO in the hood'29 surrounding the upper end of the standpipe 25 serve to break any suction effectr between the overflow chamber and float -chamber which ymight serve t-o siphon the fuel from the former` into the latter.

The overflow chamber 15 is Vvadapted to supply fuel for one jet of the compound nozzle of the carburetor, and the float chamber 2l is adapted to supply fuel for another jet thereof in a manner hereinafter described. As shown in detail in Figure there is an outlet for fuel from the standpipe chamber 15 past a, needle valve 56 controlling the outlet of fuel into the passage 52 which leads tothe chamber 51 surrounding the central portion of the compound fuel nozzle of the carburetor. The flow'past the needle valve 56 into the passage 52 is v'entirely by gravity and ordinarily is not affected by a depression induced'in the carbureting chamber' at the nozzle of the carburetor. However, the upright vent passage 58 communicating` with said outlet passage may be used to effect and control depression in the passage 52 by closing said vent passage with a plug 54 so that no air is admitted, or by reducing the suction effect in the passage 52v a. certain amount, by use of any one of a number of plugs having different sized apertures therethrough. Then any desired depression in the passage 52 may be obtained which of course affects the quantity of fuel permitted to flow to the nozzle in accordance with the requirements and characteristics of the motor to which the carburetor is connected.

The fuel admitted into the chamber 51 from the standpipe chamber 15 past its controlling andy adjustable needle valve rises in the annular passage between the outer tube 35 and the inner tubes 43 and 45. rlhe fuel rises to a level corresponding to the level of that in the standpipe chamber 15. Ordinarily the level of the fuel in the standpipe chamber corresponds to the level of theupper end of the fixed standpipe 25 and as shown in the dotted lines of Figure 2 the level of fuel in the annular chambers mentioned corresponds therewith and reaches upwardly to a point only slightly below the outlet slits 44.

rlhe other fuel level which exists in the compound nozzle is that of the fuel in the float chamber 21, and by reference to ll`igure 7, it will be seen that the level of fuel rises in the central tube and in the annular passage surrounding the same, upwardly to a point below the aperture 41 of the tube 39.

The purpose of the needle valve 6G disposed in the priming passages G1, 62 and 69 of the carburetor is to regulate the amount of air allowed to leak into said priming passages from the air inlet 65 through the peripheral groove G4 of the venturi thereby regulating the suction and consequently the quantity of fuel whichk may be drawn upwardly through the priming passages and discharge into the carburetor outlet through the passage 71 beyond the throttle valve 7.

Assume that the motor is at rest and it is desired to start the same. rPhe choker valve 12 is first closed and then the throttle valve 7. lVhen the engine is turned over, the draft created willcause a flow of fuel to take place upwardly from the float chamber 2l through the priming' passages 61, 62, 63 and 69 being discharged through the outlet 71 beyond the throttle valve 7` and of course the leakage of air past the throttle valve 7 Inany event, the suction draft due to operation of the engine is imposed upon the tip of the compound fuel nozzle in the carbureting chamber at the neck of the venturi 4. lf this suction draft is not considerable, fuel will only be drawn from the nozzle through the slits 44 in the manner pointed out in the following.

The fuel level in the annular passages of the fuel nozzle on each side of the tube 43 corresponds to that in the overflow chamber 15. The pressure on the level of fuel however in the outer annularrhamber surrounding the tube'43 is that induced owing to the suction draft on the nozzle, and the other level of fuel in the annular chamber inwardly of the tube 43, is under atmospheric pressure as will be seeni'in thcI following. rThe float chamber 21 is normally under atmospheric pressure, owing to thev provision of the :air vent 73 in the top wall thereof and as a consequence owing to the provi sion of the port 4l in the lowerI tube 39, the annular passage within said tube 39 surrounding the central tube 47 is under atmospheric pressure. This pressure effect is transmitted upwardly around the central tube 47 and is con'nnunicated thru the apertures 46 to the level of the fuel in the annular chamber.surrounding the tube 45.

As a consequence .the two. levels in the respective annular ychambers on each side of the tube 43 being subjected to different pressures, one atmospheric and the other a depression due to the suction draft through the carburetor, a change in levels of the fuel in the two chambers will take place causing the fuel to risc in the outer annular chamber and flow outwardly through the slits 44, and, of course, fuel is continual-ly supplied for this purpose from the standpipe chamber to the chamber 5l. The rate of flow of fuel to the chamber 5l is of course slightly dependent upon the amount of closure -of the passage and the demand on the chamber 15.

Fuel is `also supplied through the priming passage 7l for idlingl speeds of the engine inasmuch as the communication with the float chamber through the throttle valve shaft aperture is not entirely cut off by the preliminary opening adjustments of the throttle valve. At all times any withdrawal of fuel from the float chamber causing a lowering of the level of fuel therein, will cause the float controlled inlet valve 27 to the overflow chamber to open, thereby supplying fuel to the overflow chamber and by overflow therefrom, supplying fuel also to the float chamber.

ln order to restrict the discharge of fuel through the slits 44, in event of too great difference in pressure on the two levels within the two respective annular chambers a number' of apertures 431 and 43b are provided in the tube 43 at different levels therein so that the suction or depression effect in the outer annular chamber is partially broken as said apertures are uncovered due to the chan-ge in level of the fuel in the adjacent annular chamber. Fuel stands near the top ofthe nozzle at different levels in the annular chambers on both sides of the tube 43 during the operation of the engine. The fuel in the annular chamber within the tube 43 is under atuiospheric pressure owing to the passage through hole 41, the passage immediately surrounding the tube 47, and .aperture 46. This passage communicates the atmosphericpressure of the lower fuel chamber to the top of the fuel in the annular passage within the tube 43. The fuel in the annular passage outside the tube 43 is sub- ]ected to the sub-atmospheric pressure created in the Venturi tube as soon as the engine is startled. The differences in pressure on the fuel in the inner and outer annular chambers causes the fuel to flow from the Outer annular chamber into the intake passage. As the depression in the intake passage becomes greater, the iiow is more rapid and the level of fuel in the inner annular' chamber is lowered until one or more of the apertures 43, 43b are uncovered. Vhen these apertures are uncovered air is permitted to flow therethrough. This action lessens the depression in the inner fuel chamber as the depression in the intake passage increases and air is mixed with the fuel discharged from the nozzle. Thus a compensating effect is gained which -serves to diminish the quantity of liquid fuel drawn from the nozzle through the slits 44 in proportion to the suction effect so that a property carbureted mixture is obtained.

As the engine continues to operate, and the throttle valve is opened wider, of course, the suction effect is also imposed upon the eentral tube 47 sufficiently to cause fuel to be .drawn upwardly therethrough directly from the float chamber 2l. However, the moment the level of the fuel in the float chamber 21 tends to change owing to withdrawal of fuel therefrom through the central nozzle 47, movement of the float 33 will take place thereby lowering the lever 3l. As a consequence as pointed out, lowering of the stem :26 carrying the needle inlet valve 2T, takes place so that a flow of fuel is permitted into the overflow chamber l5 continuing until said chamber is entirely filled and the surplus fuel admitted thereto spills over the :standpipe and enters the float chamber 21 to restore the same to the predetermined level. This of course will cause elevation of the float 33 and closure of the needle inlet valve 27 supplying the fuel into the standpipe `chamber 1,5.

It. is evident that the fuel can always be supplied through the slits 44 of the com pound nozzle from the overflow chamber l5, owing to the fact thatfuel will at the same time be withdrawn from vthe float. chamber 21, causing an additional supply of fuel to i passages, one communieatingv with the top of said lower chamber, and the other communicating with the top of said upper chamber, said annular passages communicating with each other at their tops, and a veut for said lower chamber, said lower chamber venting said upper chamber through said communicating passages.

2. In a carburetor of the class described, upper and lower 'fuel supply chambers, a. single nozzle therefor7 an outer annular discharge passage in said nozzle for said upper chamber, a central discharge passage in said nozzle for said lower chamber, annular passages in said nozzle between said discharge passages, one communicating with the top of said lower chamber, and the other communicating with the top of said upper chamber, said annular passages communicating with each other at their tops7 a Vent for said lower chamber, said lower chamber venting said upper chamber through said communicating passages, and a plurality of openings at different levels between said upper chamber discharge passage and one of said intermediate passages, whereby air will be admitted to said discharge passage as the upper chamber fuel level is lowered.

In testimony whereof I have hereunto subscribed my name.

CHAR-LES L. RAYFIELD. 

